Photo: Musk Thistle in Southwestern Montana. © 2020 Delena Norris-Tull
Biocontrol TakesTime
Summaries of the research and commentary by Dr. Delena Norris-Tull, Professor Emerita of Science Education, University of Montana Western, July 2020.
Gale Lamb, Sweetwater County Weed and Pest Co-Supervisor, Wyoming, in an interview with Becky McMillen, explained one of the biggest challenges to adopting biocontrol agents. “My County has only dabbled in biocontrol. The Board members and landowners want to see results tomorrow.
“About 20 years ago, we put out insects on musk thistle and Canada thistle, on BLM ground on really steep slopes. We didn’t see any changes one year out, two years out, three years out. We thought it wasn’t working. 10 years, we went back, and we started to see some change. Those steep slopes and drainages now have very little thistle on them. It does work.
“We have some salt cedar weevils out, that we’re trying to get established. One problem in Sweetwater County is we’re at nearly 7000 feet elevation. We are having trouble getting those little bugs to overwinter at high elevation. But we have had some success with them. We’re starting to get the Board to see some of this, and we’re starting to get more insects out, especially on the … salt cedar on the Gorge. In the riparian areas, we can’t use chemicals, so the biocontrol is useful there. We have to convince the Board and the landowners to give it time.”
Lars Baker, retired Fremont County Weed and Pest Supervisor, Wyoming, describes the importance of biological controls, in an interview with Becky McMillen: “When I started in this job in 1975, we were not yet talking about biocontrol methods. We were very excited when we learned about this. We realized that weeds such as leafy spurge are not considered weeds in their natural habitats in Europe, because they have natural predators. Montana developed an insectary in Corvallis, to raise insects for biocontrol. By 1978, we had biocontrol insects to manage musk thistle. By 1990, we had our first beetles to control leafy spurge. The landowners were not excited about this at first. Finally, by 1995, biocontrol had shown its potential, and landowners finally were interested in it. One year, we were able to collect a lot of insects and re-distribute them where needed. The insects were very successful in reducing the weeds. The next year, we tried another collection day, but there were so few musk thistles left, that we could not collect enough insects for re-distribution. The musk thistle population had collapsed in one year, after 15 years of battling it! The credit goes to two species of beetles that attack the plant….
“I believe biocontrol works very well. We have some funds in our District for research on biocontrol of a number of weed species. We have learned that you do not have to eradicate a weed species. You just have to reduce the population enough to enable other plants to overcome the weeds. We still have musk thistle, but it’s no longer a problem. If you define a weed as a plant that interferes with management objectives, then musk thistle is not a weed anymore.
“Unfortunately, it’s easier for landowners to understand chemicals than biocontrol. So it’s hard to get landowners to rely on biocontrol.
“I believe biocontrol should be the first layer of technology for Integrated Pest Management. But biocontrol does not help with annual crops – with annual crops, you must get rid of the weeds immediately to preserve the yield. Just a few weeks of weed competition in the field will reduce the yield by 20% or more.
“It’s challenging to get researchers to work on biocontrol. Many grants have a two-year time limit, or the researcher is working on a master’s degree and needs to get results within one-two years. Biocontrol takes longer than that. Also, biocontrol is not profitable, in the way that chemicals are. There’s no product to sell. A landowner can collect insects on their own land, to sell to other landowners, but within three years, they won’t have a profitable number of insects anymore, because the weed population will be depleted. Or the insects will be so widespread that everyone has them and there is no longer a market. Biocontrol needs to be a public endeavor over many years. When you have the biocontrol insects established, you can work on restoring the natural ecology, planting native plants. The weeds never go completely away, but they are under control.”
The above interviews with individuals with decades of experience in weed control, provide useful insights into the challenges of implementing biocontrol. It’s not the rapid fix that landowners want. But it can be more effective in the long-term than herbicides.
Next Sections on Biocontrol Agents:
Biocontrol TakesTime
Summaries of the research and commentary by Dr. Delena Norris-Tull, Professor Emerita of Science Education, University of Montana Western, July 2020.
Gale Lamb, Sweetwater County Weed and Pest Co-Supervisor, Wyoming, in an interview with Becky McMillen, explained one of the biggest challenges to adopting biocontrol agents. “My County has only dabbled in biocontrol. The Board members and landowners want to see results tomorrow.
“About 20 years ago, we put out insects on musk thistle and Canada thistle, on BLM ground on really steep slopes. We didn’t see any changes one year out, two years out, three years out. We thought it wasn’t working. 10 years, we went back, and we started to see some change. Those steep slopes and drainages now have very little thistle on them. It does work.
“We have some salt cedar weevils out, that we’re trying to get established. One problem in Sweetwater County is we’re at nearly 7000 feet elevation. We are having trouble getting those little bugs to overwinter at high elevation. But we have had some success with them. We’re starting to get the Board to see some of this, and we’re starting to get more insects out, especially on the … salt cedar on the Gorge. In the riparian areas, we can’t use chemicals, so the biocontrol is useful there. We have to convince the Board and the landowners to give it time.”
Lars Baker, retired Fremont County Weed and Pest Supervisor, Wyoming, describes the importance of biological controls, in an interview with Becky McMillen: “When I started in this job in 1975, we were not yet talking about biocontrol methods. We were very excited when we learned about this. We realized that weeds such as leafy spurge are not considered weeds in their natural habitats in Europe, because they have natural predators. Montana developed an insectary in Corvallis, to raise insects for biocontrol. By 1978, we had biocontrol insects to manage musk thistle. By 1990, we had our first beetles to control leafy spurge. The landowners were not excited about this at first. Finally, by 1995, biocontrol had shown its potential, and landowners finally were interested in it. One year, we were able to collect a lot of insects and re-distribute them where needed. The insects were very successful in reducing the weeds. The next year, we tried another collection day, but there were so few musk thistles left, that we could not collect enough insects for re-distribution. The musk thistle population had collapsed in one year, after 15 years of battling it! The credit goes to two species of beetles that attack the plant….
“I believe biocontrol works very well. We have some funds in our District for research on biocontrol of a number of weed species. We have learned that you do not have to eradicate a weed species. You just have to reduce the population enough to enable other plants to overcome the weeds. We still have musk thistle, but it’s no longer a problem. If you define a weed as a plant that interferes with management objectives, then musk thistle is not a weed anymore.
“Unfortunately, it’s easier for landowners to understand chemicals than biocontrol. So it’s hard to get landowners to rely on biocontrol.
“I believe biocontrol should be the first layer of technology for Integrated Pest Management. But biocontrol does not help with annual crops – with annual crops, you must get rid of the weeds immediately to preserve the yield. Just a few weeks of weed competition in the field will reduce the yield by 20% or more.
“It’s challenging to get researchers to work on biocontrol. Many grants have a two-year time limit, or the researcher is working on a master’s degree and needs to get results within one-two years. Biocontrol takes longer than that. Also, biocontrol is not profitable, in the way that chemicals are. There’s no product to sell. A landowner can collect insects on their own land, to sell to other landowners, but within three years, they won’t have a profitable number of insects anymore, because the weed population will be depleted. Or the insects will be so widespread that everyone has them and there is no longer a market. Biocontrol needs to be a public endeavor over many years. When you have the biocontrol insects established, you can work on restoring the natural ecology, planting native plants. The weeds never go completely away, but they are under control.”
The above interviews with individuals with decades of experience in weed control, provide useful insights into the challenges of implementing biocontrol. It’s not the rapid fix that landowners want. But it can be more effective in the long-term than herbicides.
Next Sections on Biocontrol Agents: